pgsql: Fix one of the tests introduced in commit 52e4f0cd47.

Fix one of the tests introduced in commit 52e4f0cd47.

In the Publisher-Subscriber setup, after performing a DML operation on the
publisher, we need to wait for it to be replayed on the subscriber before
querying the same data on the subscriber. One of the tests missed the wait
step.

As per buildfarm.

Author: Peter Smith
Discussion: https://postgr.es/m/CAHut+Pv=e9Qd1TSYo8Og6x6Abfz3b9_htwinLp4ENPgV45DACQ@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/cfb4e209ec15d4a0c44efa98b2788be806a43a92

Modified Files
--------------
src/test/subscription/t/028_row_filter.pl | 2 ++
1 file changed, 2 insertions(+)